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I have installed a toploader 4 speed with a Tilton 6000 series throwout bearing and a Wilwood 13/16 master cylinder. The problem I am having is I can bleed the system and drive it. It works great for about a half an hour then it will gradually stop releasing the clutch. No amount of pumping the clutch pedal will it go into gear. I have to crank start it at stop lights. I can up shift using the throttle and clutch. Forget it if you have to down shift. It isn't going to happen. Has anyone else ran into this? I have a vacuum bleeder and tried the pumping the pedal and holding it down method also. Still the same result.

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Bruce180vf,

How did you bleed the clutch master ? not likely that you have air trapped in the release bearing assy,

but quite likely you may have air trapped in the master.

was the car on a lift when you installed and bled the master or on jack stands ?

If so you might want to check the angle of the masters bore if it was not level the air may have no place to exit.

2 different methods of bleeding come to mind here, reverse bleeding at the bleeder screw and a rubber tipped syringe to go over the bleeder (use a little Teflon tape on the threads of the bleeder) if that method does not work, I would suggest removing the master with the hydraulic line intact and then try reverse bleeding while manipulating the angle of the master cylinder.

These 2 methods have helped me in the past at both the Chevrolet and ford stores.

When I would do a S-10 chev. (external slave) I would bleed the entire system before it was ever installed.

Always remember to let gravity be your friend when bleeding a hydraulic system.

I actually bet my buddy that I could bleed the brake master on his Harley without ever cracking a bleeder, by filling,

and moving the bars and angle of the bike, takes a little patience and pumping, but no mess on a nice bike.

Oh yea, I won.

Boilermaster

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I agree, most likely still some air. It could also be the push rod is pressing against the master cylinder piston, not allowing it to fully return, which could keep the fluid in the reservoir from filling the cylinder after it has returned and released the clutch. The next time it happens try pulling up on the clutch pedal with your foot, to see if that helps.

 

 

“If you can't explain it simply, you don't understand it well enough.”

--Albert Einstein

 

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I have a McLeod hydraulic release bearing on my Boss 302. Almost 20 years. No issues.

 

You have air in the line. I’m not familiar with the Tilton, but I bet almost the same. Mine has a bleeder line with a screw in bleeder fitting. Air will get past the threads on the bleeder line if you “pump” the pedal to bleed with the valve open. It will not bleed with a mighty vac type of set up. I MUST have someone push the pedal while I crack the bleeder. Then close the bleeder before the helper allows the pedal up.

 

Now I just open the valve and let the fluid push out the bleeder, then close it mid stream.

Link to my 72 Q code: pics added 2/16/19

https://www.supermotors.net/registry/28719/88030-2

 

Link to my now sold 72 H.O

https://www.supermotors.net/registry/5858

 

My 70 Boss racecar

https://www.supermotors.net/registry/6520

 

 

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Thanks for the responses. The master cylinder has a bleeder screw and so does the throw out bearing in the top hose. I will continue to try and bleed it. The adjustment rod is coming all the way back. I can remove the rod end bolt to the clutch pedal easily. I think it is air in the system for sure.

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Thanks for all the advice. I found out that I need to adjust the throw out bearing collar to move the throw out bearing closer to the diaphragm. It is close to the extent of it's travel. Time to pull the transmission and re-adjust it.

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Thanks for all the advice. I found out that I need to adjust the throw out bearing collar to move the throw out bearing closer to the diaphragm. It is close to the extent of it's travel. Time to pull the transmission and re-adjust it.

 

Here is a link to all instruction for tilton. I would give them a look before pulling the transmission. Maybe something simple was missed like the bleed port position allowing air to remain trapped. I know on mine (american Powertrain setup) it will not fully bleed if the port is not on the top.

 

https://tiltonracing.com/technical/installation-instructions/

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  • 2 weeks later...

I pulled the transmission and remeasured everything. The throwout bearing was actually too close. Enough to cause a problem? probably not. Re-bleed the master cylinder and throw out bearing. Adjusted the clutch master cylinder rod longer and it works great. Thanks for the advice and links. Has anyone needed to re-enforce the firewall from flexing? it seems like it flex's a little. Still a lot better than mechanical linkage.

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I pulled the transmission and remeasured everything. The throwout bearing was actually too close. Enough to cause a problem? probably not. Re-bleed the master cylinder and throw out bearing. Adjusted the clutch master cylinder rod longer and it works great. Thanks for the advice and links. Has anyone needed to re-enforce the firewall from flexing? it seems like it flex's a little. Still a lot better than mechanical linkage.

  Yes.  You should re-inforce the thin firewall sheet metal.  Cut a small 1/8 plate to fit.  Or, attach a brace running from the master cylinder to the shock tower. 

 

I think Modern drive line might make a firewall reinforcement plate.  But it should be easy to make.

 

i have both on my TA car.

Link to my 72 Q code: pics added 2/16/19

https://www.supermotors.net/registry/28719/88030-2

 

Link to my now sold 72 H.O

https://www.supermotors.net/registry/5858

 

My 70 Boss racecar

https://www.supermotors.net/registry/6520

 

 

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